Abstract

(Objective)  The paper aimed to evaluate in vitro development of infective structures of Beauveria spp. strains and their effect on the growth of tomato seedlings (Solanum lycopersicum) under high-temperature conditions.

(Methodology)  The development of five strains was compared under both optimal and high-temperature conditions (up to 35°C) regarding the production of conidia, mycelium growth, and germination. Subsequently, the effect of the strain with the highest yield on the growth of seedlings of S. lycopersicum, cultivar ‘Gladiator’, was assessed under the same temperature conditions. Furthermore, each strain was identified using PCR amplification of the nuclear intergenic region Bloc and elongation factor EF1-𝛼.

(Results)  Strains were identified as Beauveria bassiana of neotropical lineage. No significant differences were found in the conidia production between treatments (p-value > 0.05), as opposed to mycelial growth. Minor but significant changes were observed in root-to-surface ratios but not in any other evaluated variables, and only for seedlings treated with strain H-31.

(Conclusions)  The entomopathogenic potential of B. bassiana was determined under environmental stress conditions, such as high temperatures typical of tropical climates. This study also lays the groundwork for the bioprospecting of thermotolerant microorganisms with agrobiotechnological potential in global warming scenarios.

Keywords: thermo-tolerance; entomopathogenic fungi; biologic control; growth promoter; physiological stress